Mine is 277g incl. guylines, Stuffsack is 11 g. Seam sealing is not necessary, and I have spent plenty of nights in the rain in it without problems, also a thunderstorm didn't manage to drive any rain through the seams. Really awesome shelter.

[Which leads me to conclude that seam sealing is overrated/ necessary if the stitching is rubbish =]

I've had one of the original SpinnShelters (with the two-flap door in the rear) for about seven years now and have used it in all sorts of weather, from steaming summer days to torrential rains and in spite of not having seam sealed it never had a problem. It's the shelter I inevitably always come back to after trying everything else. Mine weighs 268 g (9.5 oz.). Guylines, 28 g. Stuff sack 15 g. I also use a short rear aluminum pole, cut to the height of the rear peak in storm mode (I raise the front of the shelter, but not the rear) instead of a regular trekking pole (I prefer carrying only one trekking pole), which weighs 32 g.